(a) Technical Field
The present invention relates to a phased array transducer using a magnetostrictive phenomenon. More particularly, the present invention relates to a phased array transducer which can transduce shear horizontal bulkwaves for forming multiple channels without using a separate waveguide or waveguide structure.
(b) Background Art
A magnetostrictive transducer module for transducing guided ultrasonic waves has been disclosed in Korean Patent No. 10-1061226 filed and registered by the applicant of the present invention. As disclosed in Korean Patent No. 10-1061226, various types and modes of guided ultrasonic waves may exist according to the shape of a separate waveguide or waveguide structure.
Particularly, in the waveguide or waveguide structure is implemented as a plate-shaped structure, two kinds of guided ultrasonic waves, i.e., Lamb waves and shear horizontal (SH) waves may be used according to the direction of medium displacement, and an infinite mode exists in each of the Lamb and SH waves.
Since the dispersion curves of modes in the SH wave do not intersect with one another, the separation of modes from a measured signal is relatively easy, and the speeds of the modes are sequential. Thus, the operation of identifying the modes can be easily performed. In the shear horizontal wave, only the SH0 mode exists at no more than cutoff frequency of the SH1 mode, and thus influence of other modes can be excluded. More importantly, the SH0 mode is the unique mode of nondispersive waves, of which speed is not changed depending on its frequency. For these reasons, the mode of the SH wave, particularly the SH0 mode is preferably used in a nondestructive test based on guide ultrasonic waves.
Like the magnetostrictive transducer module disclosed in Korean Patent No. 10-1061226, a magnetostrictive transducer module including coil is manufactured, so that it is possible to transduce an ultrasonic wave having a directional property in the guided ultrasonic waves.
However, it was conventionally difficult to generate an ultrasonic wave having a directional property desired by a user. In addition, a transducer or transducer module including a separate waveguide or waveguide structure was used as an array sensor to be connected to a certain place. Therefore, the reduction in efficiency due to the use of the waveguide was unavoidable.
Since the thickness of a magnetostrictive patch used in the conventional magnetostrictive transducer or magnetostrictive transducer module was thin, it was impossible to erect the magnetostrictive patch. Further, the magnetostrictive patch required a relatively wide area, and therefore, it was disadvantageous to use the magnetostrictive patch.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.